Purpose To evaluate the cerebral haemodynamics and vasoreactivity in the posterior cerebral artery (PCA) in patients with primary open angle glaucoma (POAG) by using transcranial color Doppler.
Menthods Clinical diagnosed POAG patients with obvious visual field loss and neural damage were enrolled. All subjects had best-corrected visual acuity of 20/40 or better. Only patients of 40 to 60 years old and has no history of cardiovascular disease or severe systemic and metabolic disorders were included. Age and gender matched healthy individuals were enrolled as controls. After routine ophthalmic examination, TCD measurements were taken in a dark and quiet room. Heamodynamic parameters (Mean and peak velocity and pulsatility index) in bilateral PCA were recorded under baseline, when receiving monocular hyper-threshold light stimulation, and when performing slow (0.1Hz) or fast respiration (2Hz). The eye with the more severe visual field defect was chosen in glaucoma patients, while in controls the study eye was chosen randomly.
Results Totally, 17 POAG patients and 12 controls were included. No difference in heamodynamic parameters (velocity and resistance) of PCA between POAG patients and their controls was observed at baseline. When receiving light stimulation, both the POAG patients and controls show a response of velocity increase in bilateral PCA comparing with baseline. However, mean velocity (MV) change percent of bilateral PCA in POAG patients was significantly lower than that of controls. In conditions of slow and deep respiration, POAG patients and controls exhibited similar PCA responses, shown as decreased velocity and increased vascular resistance. Fast and deep respiration resulted in similar responses of PCA as slow and deep respiration. No obvious difference was observed between two groups.
Conclusion Haemodynamic response of PCA to visual stimulation is significantly decreased in POAG patients, while vasoreactivity of these arteries to systemic stimulation is relatively reserved. Cerebrovascular insufficiency in POAG patients does exist, which maybe is not organic but result from neurodegeneration in the visual pathway through neurovascular coupling.